Enhanced transient angle stability control of isolated power grid based on phase sequence exchange

Abstract

An isolated power grid (IPG) lacks the support of the external power grid, and a single generator or load accounts for a large proportion of the total capacity. Once transient angle instability, the generator and load shedding is not effectively. Phase sequence exchange (PSE) uses power electronic devices to switch the three-phase sequence, thereby reducing the power angle of the generator by 120° and preventing the system from losing stability. This paper proposed a PSE scheme for transient angle instability applied to IPG. The local measurements of IPG are used to identify the critical generator, and the system trajectory is obtained through large-step integration. The stability is assessed by the concavity of the trajectory. Once the trajectory swings from the concave area to the convex area, the IPG loses transient stability, at which point the generators in the critical cluster simultaneously PSE prevent transient instability. Based on Simulink and RTDS platform, the scheme is verified in a 39-bus 10-machine system and an existing IPG system. The results show that the proposed scheme can effectively restore the stability of the IPG, outperforming generators and load shedding.

Keywords

• Isolated power grid
• Phase sequence exchange
• Transient angle stability